title: Spatial and temporal requirement of defective proventriculus activity during Drosophila midgut development.
abstract: The Drosophila middle midgut cells derived from the endoderm develop into four distinct types of cell. Of these cells, copper cells have invaginated microvillar membranes on their apical surface, and they are involved in two distinct functions, i.e., copper absorption and acid secretion. The homeobox gene defective proventriculus (dve) is expressed in the midgut, and two transcripts, type A (∼4.9kb) and type B (∼3.5kb), have been identified. We isolated the deletion allele dve(E181) that completely removes the first exon for type-A (dve-A) transcript. Dve expression pattern in dve-A mutant background indicates that isoform switching is dynamically regulated in a cell-type specific manner. Using RNAi for dve-A, we examined spatial and temporal requirement of the Dve-A activity. Early Dve-A activity is required to repress isoform switching in copper cells, and for establishment of two gut functions. Late Dve-A activity in copper cells, but not in adjacent interstitial cells, is required for acid secretion, while the activity is redundantly required in both cells for the copper absorptive function. Furthermore, ectopic type-B expression in larval copper cells specifically impaired the copper absorptive function. These results provide insight into molecular mechanisms to establish functional specificity.
authors.affiliation: Graduate School of Natural Science and Technology, Okayama University, Tsushima-naka, Kita-ku, Okayama, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Shinobu
authors.initials: S
authors.lastname: Fujiwara-Fukuta
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yorimitsu
authors.forename: Suzuka
authors.initials: S
authors.lastname: Tanaka
authors.forename: Ryunosuke
authors.initials: R
authors.lastname: Minami
authors.forename: Lily
authors.initials: L
authors.lastname: Shimooka
authors.forename: Hideki
authors.initials: H
authors.lastname: Nakagoshi
mesh_terms: D000042:Absorption; D000818:Animals; D003300:Copper / Q000378:metabolism; D004064:Digestive System / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics / Q000254:growth & development*; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007814:Larva / Q000235:genetics / Q000254:growth & development*; D009928:Organ Specificity; D020033:Protein Isoforms; D017384:Sequence Deletion
chemical_list: D029721:Drosophila Proteins; D018398:Homeodomain Proteins; D020033:Protein Isoforms; C114494:dve protein, Drosophila; C059843:lab protein, Drosophila; D003300:Copper